A spiteful Staten Island woman terrorized her ex-husband’s new fiancée — assaulting her and trying to get her fired from her job, a new lawsuit charges.

The trouble between Mary Lou Malczewski and Irina Zamfir — who is engaged to Malczewski’s ex, William — began in 2013 with the ex-wife hurling racial slurs at the Romanian beauty via text and
threatening her life, according to the lawsuit filed Thursday in Brooklyn federal court.

The mom of two also twice phoned Zamfir’s bosses in a failed effort to get her fired for “engaging in inappropriate sexual activity” in the office, the suit alleges.

The row between the two women, both 47, escalated when two years later, Malczewski was arrested for allegedly attacking Zamfir and stealing her cellphone at a shopping center.

Malczewski and her ex — a ­retired NYPD officer — finalized their divorce in February 2015, sources said.